Since conversions of the 58 mm rokkor seem to be increasingly popular, I thought I'd post my own version here, which I did a few weeks back. My interest was originally sparked by Pete Ganzel's conversion gallery on pbase and Arkku's post here gave me further inspiration. Then I finally got hold of one of these lenses in great condition at a reasonable price on ebay. My conversion was done using an M42 adapter and some pieces of plastic as a spacer. More detailed description is given in my corresponding gallery on pbase. Here are shots of the converted lens and a couple of samples:

1/1250s, f/1.2, iso100

1/640s, f/2.0, iso100

1/1500s, f/1.2 (I think), iso100

100% crop of the above shot

I really love the lens. The bokeh is very good and sharpness is good at f/1.2 if you get the focusing right (which ain't easy). From f/2 my copy is very sharp all the way into the APS corners. It is a way better lens than the AF 50mm/1.7, which I like a lot too.

if that last one really is wide open, thats a remarkably 100% crop IMHO. I never believes it was that good wide open. Unless you have a very good sample or something .

Thanks for sharing it & well done.

I'm myself not 100% sure if that last one was really at f/1.2. At least I can't find any traces of the eight sided aperture in the OOF area. Possibly the lens was set between f/1.2 and f/2 for this shot. There's no click stop but it's still possible to set it there.

Here's a 100% crop of the other f/1.2 shown above, and IMO it's not bad either although maybe not quite as good as the other one.

I did my conversion in the same way couple of months ago.
Recently after reading Shao's post conversion with rom chip, I order a M42 adapater with rom chip from JamesLaoT and replace the adapter and it work perfectly with focus confirmation and exif info.
The only drawback is James adapter measures 64mm in diameter and I have to have my brother-in-law, he's a mechanic, to trim it down to 62mm in order to fit the lens barrel.
The other way to work around is just to order a rom chip with data 58/1.2 from James and glue the chip to the adapter like Shao. But I figure this would be harder for me.
Just to share my experience and joy of having a f1.2 lens.

The only drawback is James adapter measures 64mm in diameter and I have to have my brother-in-law, he's a mechanic, to trim it down to 62mm in order to fit the lens barrel.

When I did my conversion (first non-electric, later added a chip from Lao to another M42 adapter), I sanded down the ring on the lens instead of the adapter. It doesn't require much skill or finesse, as it is just the outer rim which needs to go. This makes the modification somewhat less reversible, but that is not an issue for me.

teko wrote:

... some pieces of plastic as a spacer

Why plastic? I'd be a bit worried about how "even" you can get their height, plus each piece looks so thick that you can't adjust the spacing very small increments that way. Personally I recommend household aluminium foil. Fold it many times to make thick sheet, cut a ring of suitable size out of that, make holes for the screws, and then you can adjust the position by removing single layers of the aluminium sheet one at a time. With this method I got my infinity focus position so accurate that stars appear pin-sharp at the infinity focus position, even wide open: astrophotography without focusing. =)

I don't have the means to turn stuff from metal and plastic was the easiest thing to cut I had at home. Also I had a sheet of plastic which was exactly 1 mm thick, so two of them gave exactly the thickness which I needed for the conversion. I also wanted to do the conversion fully reversible to maintain the resale value just in case.

Of course it's great that you got it working with plastic, I personally just find the suggested aluminium/baking foil a lot easier to cut with regular scissors than plastic, and the thickness is way more adjustable. And it's equally reversible. But, nothing wrong with the plastic solution if it suits you and you can live with the way it looks, you'll have a great lens regardless of what's inside the mount!

I had one of mine converted by means of an aluminum spacer and a genuine Minolta 50/1.7AF mount flange part I'd bought from Minolta in NJ for $15.

I wonder if anybody had ever contemplated doing a full AF conversion. I have a broken 50/1.4 and 50/1.7 I'd bought on eBay - however the part that I feel could really work is the cam barrel set from the 85/1.4. Unfortunately it cost over $300 new (at the same time when the above flange had cost $15 - probably meaningfully more from SONY now)

I wish SONY would reintroduce this lens in AF mount, with ultrasonic focusing, and with tilt to control DOF. Ideally also add VFC control. Then it would be the ultimate DOF machine :-)

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